1. Field of the Invention
The present invention relates to a method for preventing, reducing, stopping and/or arresting sulfuric corrosion of metal surfaces.
More particularly, the present invention relates to a method preventing, reducing, stopping and/or arresting sulfuric corrosion of metal surfaces in contact with fluids that contain agents that cause or promote sulfuric corrosion through addition of a compound having a interaction potential for the metal surface that is greater than the interaction potential for the sulfidizing species in the fluid.
2. Description of the Related Art
Sulfuric corrosion (sulfidation) is quite common in several chemical processes, such as oil and gas processing, combustion of fuels containing sulfur, sulfur production, etc. The usual remedy is to use materials that have a high resistance to sulfidation.
It is well-known that in cases where a gaseous atmosphere containing oxygen, sulfuric corrosion can be ameliorated and slowed by oxidation. In such cases, a layer of oxide forms on the surface of the metal preventing sulfur penetration. Sulfides are formed and deposited on the surface of this oxide layer. The metal surface remains protected during the initial oxidation period, until breakaway corrosion is initiated, which is then followed by rapid sulfidation attack.
Thus, in low oxygen environments, the rate of sulfuric corrosion depends mainly on the materials used and on the concentration of sulfur containing compounds in the contacting fluid or atmosphere. In an environment with sufficient oxygen, corrosion becomes a competition between oxidation and sulfidation.
Thus, it would represent a significant advancement in the art to have a method that prevents sulfuric corrosion of metal surfaces in contact with fluids containing sulfur compounds.
The present invention provides a method of preventing, reducing, stopping and/or arresting sulfuric corrosion sometimes referred to herein as sulfidation of metal surfaces in contact with fluids containing sulfur containing compounds capable of sulfidizing the metal surfaces. The method comprises adding an anti-sulfidation composition to the fluid on a discrete or continuous basis in an amount sufficient to prevent, reduce or stop sulfidation of the metal surface, where the anti-sulfidation composition comprise a compound that has a greater potential for interacting with the metal surface than the sulfur containing compound and is preferably a phosphorus-containing compound.
The present invention provides a method of preventing sulfuric corrosion of metal surfaces in contact with fluids containing sulfur containing compounds capable of sulfidizing a metal surface, where the method comprises adding a phosphorus-containing compound to the fluid on a discrete or continuous basis in an amount sufficient to prevent, reduce or stop sulfidation of the metal surface.
The present invention also provides an apparatus for introducing an anti-sulfidation composition into processing equipment in contact with fluids containing sulfur containing compounds capable of sulfidizing metal surfaces in an amount sufficient to prevent or to reduce or stop additional sulfidation of the metal surfaces of the equipment. The apparatus includes a reservoir of the composition and an injector system in fluid communication with the reservoir and the equipment for metering into the fluid in contact with the equipment the sufficient amount of the composition. The composition comprises at least one anti-sulfidation composition, where the anti-sulfidation composition is a compound that has a greater potential for interacting with the metal surface than the sulfur containing compound and is preferably a phosphorus-containing compound.
The present invention also provides a metal surface in contact with fluids including sulfur containing compounds capable of sulfidizing a metal surface treated with an anti-sulfidation composition in an amount sufficient to prevent, reduce or stop sulfidation of the metal surface. The composition comprises at least one anti-sulfidation composition, where the anti-sulfidation composition is a compound that has a greater potential for interacting with the metal surface than the sulfur containing compound and is preferably a phosphorus-containing compound.
The present invention also provides a method for pre-conditioning a metal surface to prevent initial sulfidation including contacting the metal surface with an effective amount of a phosphorus-containing compound sufficient to form a protective phosphorus or phosphorous oxide containing on the metal surface.